Various tubular devices exist to access different portions of the gastrointestinal tract. For example, oro-gastric or naso-gastric tubes exist to suction secretions and fluid from the stomach as well as to deliver fluids and feeding solutions. Bowel waste management systems exist to collect the feces of incontinent patients. Devices whose lumens communicate with the gastrointestinal tract, broadly referred to as enteral devices, are also used to deliver medication. For example, U.S. Pat. Nos. 8,123,732 and 7,147,627 describe a port for a bowel management system that can be used to administer medication. Indeed, the administration of medication into the rectum is playing an increased role in medicine, especially in palliative care for symptom control.
Despite the increased interest in enteral administration for medical care, there have recently been serious adverse outcomes related to the misconnection of various medical devices to incorrect ports of medical tubes. Significant complications including deaths have occurred when feeding solutions, non-sterile or suspended medications meant to be given into the enteral tract have been inadvertently injected into the blood stream. Indeed, ISO standards currently demand, and the FDA will soon require, that ports for enteral devices be rigid, non-flexible, and unable to connect to Luer type connections and even other devices such as medical oxygen, and suction apparatuses in order to avoid misconnection and injury to patients.
It is of utmost importance to provide a medication port for enteral devices which does not mate to a Luer type syringes or other medical devices. A rigid female port which connects only to an enteral delivery device, such as an enteral adaptor or enteral tapered syringe, and is incapable of connection to a Luer type syringe is one way to minimize the probability of introducing enteral solutions intravenously. As such, there is a need for an improved medication administration port or assembly to prevent potential health and safety issues associated with these types of enteral devices. Therefore, in one aspect, embodiments described herein provide for an administration port/assembly that connects only with enteral specific devices (e.g. enteral syringes) for medication administration to the gastrointestinal tract.
Another challenge for enteral patient care has been the spread of infection in healthcare environments and the community at large. Antibiotic resistant infections are a $20 billion dollar problem in the United States. It is of utmost importance that devices engineer safety features within the design which minimize the risk of bio-hazardous contamination of the environment. Medication ports or assemblies attached to body cavities that do not need to extract fluid from the body cavity should be designed in such a way that retrograde flow cannot occur. Delivery assemblies such as ports on devices which only administer medication should be one way, for delivery only. Especially when these tubes enter orifices which contain high levels of microbes such as the rectum, they should not allow for any retrograde flow to decrease the possibility of environmental contamination of bio-hazardous substances.
Although preventing retrograde flow in parenteral medication and fluid administration has been addressed to some degree, the same attention has not been given to enteral administration. For example, U.S. Pat. No. 3,416,567 and U.S. Pat. No. 5,098,405 teach valves for parenteral infusions, but do not teach valves for enteral application. Furthermore, the valves taught for parenteral administration would fail in the context of enteral administration because of the differences between the sterile, controlled solutions used in parenteral administration and enteral formulations.
Typically the port of enteral medical devices through which medication can be administered has been a non-valved, simple bi-directional port, sometimes including a capping mechanism which is used for multiple purposes including irrigation, fluid and medication administration, suctioning, and sampling. Furthermore, these ports are often soft and flexible, and mate non-restrictively with enteral, catheter tip, and luer type syringes and connectors. The need for a one-way valved main or side port which can only connect to an enteral device with enteral tip dimensions has not been addressed for enteral devices. As such, in another aspect, some described embodiments herein provide for an enteral-only medication administration port or assembly with a one or uni-directional valve for use with an enteral device. Advantageously, a one-directional valve has the added benefit of ensuring that the appropriate dose of the medication is administered without any leakage out of the enteral device (e.g. rectal tube).
In addition to the above, there is also a need for an enteral delivery device such as a port and/or delivery assembly that maintains the suspended form of viscous fluids for enteral administration to a patient. Unlike medications given intravenously which are administered in solution or in suspensions of very small particulate size (usually less than 1 micron) form, medications given enterally are often large particulate suspensions with particulate sizes 100 of microns in diameter. For instance, solid medications are many times crushed and suspended in water to be injected through these devices which can have a very large particulate size. These substances can clog valves, or cause them to stick in the open position unless the interior of the valve is designed allow these medications to remain suspended as they pass through the valve.
Many valves exist which facilitate parenteral injection of fluids into the body as opposed to enteral administration. These parenteral valves usually open when a syringe or intravenous connector is attached and close when they are removed. They are usually attached to a fluid transmission tube of some type, such as intravenous lines for injection into the blood stream. Existing parenteral valves are limited in their utility as they are not designed to produce turbulent flow. Turbulent flow is important within a valve used in a device that transmits enteral medication formulations. Turbulent flow keeps the walls of the valve from building up particles which can eventually clog the valve and serve as a breeding ground for bacteria.
Turbulent flow is especially important for enteral devices which administer fluids in suspension, via the gastrointestinal tract (e.g. oral, gastric, and rectal delivery). If flow is not turbulent through an enteral device the particles in suspension settle or flocculate, causing clogs. Emulsions also cause clogging. Although they do not settle and are more stable than suspensions, they can cause residue buildup on the wall of the valve which eventually clogs the device. Residue buildup can cause bacterial growth and is a cause of bacteremia by intravenous devices. Total parenteral nutrition (TPN) is an example of an emulsion given intravenously. Its high nutrient composition makes it a strong catalyst for bacterial growth. Blood is also an emulsion and is the most common reason for clogging in intravenous lines, and also encourages bacterial growth.
As mentioned, an enteral fluid delivery device, such as an enteral administration assembly or port, is needed which will not clog or allow for residue buildup within itself or within the fluid transmission tube immediately adjacent to it. Creating such a device must take into account the complex fluid dynamics associated with emulsions and suspensions. The first important consideration is the type of flow within the device and through the fluid transmission tube. Turbulent flow favors a stable suspension as opposed to laminar flow. Destabilization of the suspension or emulsion can occur more easily in laminar flow as viscous forces are encouraged over inertial forces, causing flocculation, coalescence, or sedimentation as particles begin to congregate.
Another benefit of turbulent flow has to do with the interaction of the fluid with the wall of the delivery device itself. In laminar flow, suspensions and emulsions can settle easier, as flow near the wall of the delivery device slows to basically a complete stop. This decreased flow velocity zone is called the boundary layer. With turbulent flow, random movement of fluid in different vectors and an increased overall kinetic energy creates a cleaning or scouring action against the wall of the device, as particles and water hit the wall from different trajectories loosening and removing deposits. In laminar flow on the other hand, fluid moves parallel to the wall slowing to a complete stop at the boundary layer. This encourages destabilization and formation of deposits on the device walls which can eventually form a clog, and also encourages bacterial growth and biofilm formation. In intravenous devices, blood cells tend to accumulate on the walls of valves and the inner lumen of the line creating a high potential for bacterial growth and can cause sepsis in the patient.
Another consideration in the delivery device design is the diameter of the passageway. The potential to create turbulent flow increases with passageway diameter and fluid velocity. This is shown in the Reynolds equation which gives us a measure of the ratio of inertial forces to viscous forces. Thus, the Reynold's number can predict laminar vs. turbulent flow. As discussed above, dynamic states in which viscous forces overpower inertial forces favor laminar flow. Laminar flow occurs at lower Reynolds numbers and turbulent flow occurs with higher numbers as shown in the equation below. Both tube diameter and velocity are directly proportional to the Reynold's number.
Reynolds Equation
      Re    =                  ρ        ⁢                                  ⁢                  vD          H                    μ        ;where:                DH is the inner diameter of the tube or device.        v is the mean velocity of the object relative to the fluid        μ is the dynamic viscosity of the fluid        ρ is the density of the fluid        Re is the Reynolds number        
With the small diameter of most medical tubes, valve assemblies, and intravenous lines, turbulent flow is almost impossible to achieve without a turbulator within the lumen which increases the inertial forces of particles moving through. A turbulator is simply a device which turns laminar flow into turbulent flow. It increases the kinetic force component within the system. But in order to create turbulence even with the assistance of a turbulating device, fluid velocity within the lumen must be fast enough to generate the kinetic energy needed to transition flow from laminar to turbulent. Tube diameter has a powerful effect on flow. If the diameter within, for example, an enteral administration device becomes too small, flow slows, encouraging laminar flow and destabilization, or stops completely as there will eventually not be enough pressure to force the fluid mixture through the device for delivery to the patient tube. In other words, turbulent flow can easily transition to laminar flow if the diameter of a tube through which a fluid travels decreases, and if the kinetic energy of the suspended mixture is allowed to dissipate.
Given these considerations, another aspect of the invention provides for enteral delivery devices or assemblies (e.g. ports) that include turbulators for creating turbulent fluid flow to maintain suspended mixtures and prevent sedimentation or flocculation.
In summary, embodiments described provide for, among other things, an improved valved enteral administration assembly such as a port for delivery of medications to the rectum or other parts of the gastro-intestinal tract, which are capable of transmitting emulsions, large particulate suspensions, and viscous solutions typical of enteral medications, and which can be permanently disposed on the enteral medical device. In some variations, the enteral administration port or assembly is incompatible with Luer connectors. Additionally, some embodiments include a valve or valve mechanism which provides for uni-directional flow and prevents retrograde flow—delivering substances to the body cavity, but not allowing for withdrawal from the body cavity. For those cases where bi-directional flow is desired such as a sampling-irrigation port, as opposed to simply a medication port, an embodiment with a bi-directional valve is also contemplated and described herein.